For my senior capstone I worked with a Native American reservation (in WI) on a downtown revitalization project. The governmental structure and land ownership patterns of the community posed some interesting challenges but also presented a lot of unique design and planning opportunities. It was also a tight knit community that was very receptive to ideas like food independence and and sustainable usage of natural resources. Of course, none of this would necessarily apply to all tribes, but it may be worth looking into. If your school has an extension program, they may do some work with tribes in the state. I don’t know the best way to approach tribes in other states if you’re set on working in Arizona but I’ll think about it.